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Out of that roughly 3000 stars we can see with the naked eye, how many of those observed stars do you think would be hospitable to our form of life. Very few is my guess.
You would be guessing wrong! Every single one of them will have a "zone" that a planet could orbit in that would provide all the things that we see here as far as the chemistry goes. And again, while our type of chemistry (carbon based) may seem the most likely type, discovering life forms on a body like Europa would surely throw a lot of monkey wrenches into any speculation.
Look, I don't disagree that we don't know.
heck, I don't even disagree that advanced ETI is quite unlikely/rare.
What I do dissagree with, and have a lot of disrespect for are your assertions as fact that it has to be on a planet like earth, and life forms that are earthlike, with humanlike psychology. Those assertions are totally unfounded, if not downright delusional.
Europa should prove very interesting as scientists/astrobiologist think there may be a liquid water world there under the mantle of ice, possibly heated by the moons own core. I think more effort should be made to that moon than to Mars which seems to be a dead world like our moon. Imagine the repercussions if some kind of life is found there under all that ice.
Europa should prove very interesting as scientists/astrobiologist think there may be a liquid water world there under the mantle of ice, possibly heated by the moons own core. I think more effort should be made to that moon than to Mars which seems to be a dead world like our moon. Imagine the repercussions if some kind of life is found there under all that ice.
The bottom line is that a couple billion years is too long.
It will take less that 10 million for human beings to colonize the whole galaxy.
The Milky Way existed for billions of years before our sun was even born. So, logically, if life like us is common, they should be everywhere now.
The bottom line is that a couple billion years is too long.
I deal with religious people who refuse to see evidence or turn away for logical constructs in these chat forums. Mormons, Muslims, Scientologist and the SETI faithful all have the same mind set to me.
Snake Oil is Snake Oil. Putting money into SETI when it can help us in other ways hurts us all.
Do you have any support for that statement?
Because that seems more like a statement of faith than anything that the "SETI faithful" have said in this thread.
There are at least two things wrong with this statement. One is that the search for ETIs is not the search for human beings. The other is the point Roboramma made. That point is the same basic idea I've been listing as a refutation for the argument that ETIs do not exists based on Fermi's Paradox. There are a number of other possible explanations for the lack of evidence of ETIs at this point.
The Milky Way existed for billions of years before our sun was even born. So, logically, if life like us is common, they should be everywhere now.
That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.
Putting money into SETI when it can help us in other ways hurts us all.
This point too has been covered. It's a relatively small amount of money. None of it is taxpayer money. There are potential payoffs for this kind of project--even aside from the long-shot payoff of finding a signal from an ETI.
That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.
But we have been here less than 50.000 years as a civilization. If we manage to survive the next 100.000 years, the galaxy will be at our mercy. I'm certain we will have colonies on at least half the solar system, and probably robotic probes searching for signs of life in other nearby galaxies.
That's not logical. There could be other civilizations more or less equal to our own, and we would not expect them to have filled the galaxy with evidence of their existence since we have not done so.
In that numbered list of reasons you have posted before, could you run down the minimum that you think need to be true for this to be the case?
The scenario where the galaxy is populated by civilizations rougly equivalent to our own and no others more advanced who've gone on to colonize seems to require a lot of conditions to have been true for all civilizations that ever existed. Or it seems to require that civilization is destined to appear simultaneously and this is the time.
Logically, for the lack of evidence to point to the conclusion that ETIs don't exist, absolutely none of the other explanations can be possible. I've stated this elsewhere. You'd have to refute all the other possibilities.
Exactly. So the only example we have of an intelligent civilization doesn't support any conclusions you want to make about longevity of civilizations and what must inevitably happen.
I have ceded the fact that the lack of evidence proves that no super-advanced civilization exists that has made evidence of their existence ubiquitous in the galaxy. (And even in that scenario, it doesn't prove that a long-lived advanced civilization doesn't exist. If you're going to assume super-advanced technology, why not also assume the ability to hide evidence of their existence from us? I don't think such a thing is very likely, but I'm just pointing out the logical flaw in your argument.)
The scenario where the galaxy is populated by civilizations rougly equivalent to our own and no others more advanced who've gone on to colonize seems to require a lot of conditions to have been true for all civilizations that ever existed. Or it seems to require that civilization is destined to appear simultaneously and this is the time.
I don't follow. The scenario where the galaxy is populated by civilizations roughly equivalent to our own is consistent with the lack of evidence. (And it doesn't require there to be no others more advanced, but merely no others more advanced that have made evidence of their existence ubiquitous in the galaxy. What if that advanced civilization has colonized say 1/4 of the galaxy but not our immediate area?)
Nice sidestepping, please explain what it would it take to make your list of numbered "reasons" consistent with either the scenario you mentioned before or the scenario you're positing now.
Nice sidestepping, please explain what it would it take to make your list of numbered "reasons" consistent with either the scenario you mentioned before or the scenario you're positing now.
I sidestepped nothing. My list of is not a list of "reasons"--it's a list of alternative possible explanations for the Fermi Paradox (that is, for the lack of evidence of the existence of ETIs). In order for the explanation, "no ETIs exist" to be proven, you would have to eliminate all these other possibilities. If even one of them remains a possibility, then the lack of evidence fails to prove that ETIs do not exist.
I suggest you read through the thread. All of this has been covered. (And I did answer your question about my numbered list. And in at least several versions of my numbered list--I've repeated it several times over the one year plus life of this thread--I made this very clear by saying that if any one of these explanations remains, it refutes the argument amb has been making: that the lack of evidence of ETIs proves their non-existence.)
Basically this argument depends on a great number of assumptions to be true, and we have no reason to claim that all these assumptions are true.
For the record (and about the twentieth time), my position on the question of the existence of ETIs is simply that we don't know. I am in no way claiming proof of the existence of ETIs.
Agnosticism is a fair view to take in this regard. But it's not all that different to been agnostic in religious matters. The center position is for people who will not commit to one way or the other, fence sitters if you prefer.
If on the other hand, one looks at the age of this universe, the unlikely odds of life starting from the raw elements that were made in the original B/B, and having to be processed in giant stars that had to explode to spew material that was produced in the stars core in order for planets to form into the vast reaches of space, a cycle that is ongoing, death of one leads to life of another, the energy never dying, but recycled over and over. Perhaps in some little corner of the universe, the first elements came together to produce more elements that finally over who knows how much time produced the first microbes and or cell.
I have argued before, that if this planet was completely destroyed, and every hint of life came to an end. What are the chances life will once again start here like it did 4 billion years ago? Let alone a homo sapien like creature.
I don't follow. The scenario where the galaxy is populated by civilizations roughly equivalent to our own is consistent with the lack of evidence. (And it doesn't require there to be no others more advanced, but merely no others more advanced that have made evidence of their existence ubiquitous in the galaxy. What if that advanced civilization has colonized say 1/4 of the galaxy but not our immediate area?)
I don't really think you can make that argument: if there are other civilizations we don't expect them to have preferentially arisen at a point in time close to us. But the time in which they could have arisen is large enough that not arising at exactly the same time means they'd likely be very much older.
Of course, if there are only a few civilizations, its possible (though unlikely) that just by chance they may have arisen at a time close to ours. But if there are very many, that they all did is pretty damn unlikely.
Which suggests that if there are other civilizations they either have a very different sort of development from us (for instance, they may have mastered chemisty, but not other forms of technology), or they are very much more advanced than us.
Note, however, that more advanced than us does not imply capable of interstellar travel, as we simply don't know what is required for that.
I don't really think you can make that argument: if there are other civilizations we don't expect them to have preferentially arisen at a point in time close to us. But the time in which they could have arisen is large enough that not arising at exactly the same time means they'd likely be very much older.
Of course, if there are only a few civilizations, its possible (though unlikely) that just by chance they may have arisen at a time close to ours. But if there are very many, that they all did is pretty damn unlikely.
Which suggests that if there are other civilizations they either have a very different sort of development from us (for instance, they may have mastered chemisty, but not other forms of technology), or they are very much more advanced than us.
Note, however, that more advanced than us does not imply capable of interstellar travel, as we simply don't know what is required for that.
ETA: I never said anything that claims that the civilizations would have had to arise preferentially close to us in time. (See below.) However, that is in fact one of the Rare Earth arguments--that there hasn't been enough time since the formation of our galaxy, since heavier metals require at least a couple of generations of stars to have preceded the present. (I linked to something recently though that counters this--the first galaxies formed earlier than was previously thought.) And it fits with the point I've been making again and again: no more time has passed here than elsewhere in the galaxy, and yet here we are.
Yes. I agree. [ETA: with you final sentence, that is.]
My point is that it is possible for there to be plenty of civilizations at more or less our level. But I've also said, as you do, that it's also possible that there are any number of other explanations for why we haven't seen evidence of ETIs yet.
I've listed them several times. One is, as you say, there could be older and more advanced civilizations that aren't capable of interstellar travel (either because it's not practical, it's not feasible, or for some reason they all lack the motivation to use it).
It could be that no technological civilization lasts that long (and that position is quite credible given how close we've come to ending our own civilization, and the fact that we've yet to deal with several very daunting problems, like population). That would result in the scenario described above--where the only civilizations extant in the galaxy are more or less on par with our own, and we lack the ability to detect them (or them us, or any one to detect any other) unless we get extremely lucky.
Agnosticism is a fair view to take in this regard. But it's not all that different to been [sic] agnostic in religious matters. The center position is for people who will not commit to one way or the other, fence sitters if you prefer.
That's absurd. When we are ignorant, scientifically the only reasonable position is to say we don't know.
Agnosticism as the term originated referred to the belief that God is unknowable (sort of like deism). As it's used today, it is the belief or doctrine that we don't (or can't) know whether or not God exists. (And seen that way, it's the only reasonable position, and is not a substitute for being an atheist--in fact all atheists are also agnostics.)
Atheism is either the lack of belief in the existence of a god or gods (weak atheism, or what I think of as a[theism]; or the belief in the non-existence of a god or gods (strong atheism, or what I think of as [athe]ism). From a scientific or skeptical point of view, I see atheism as the provisional acceptance (or rejection) of a proposition based on what the evidence points to. (Either the acceptance of the proposition, "No god exists" or the rejection of the proposition, "A god or god exists.")
So, while we are all "agnostics" wrt the existence of ETIs (that is we don't know), we lack the evidence to provisionally come to the conclusion that ETIs do not exist. That is, there's no reason at this point to believe that ETIs don't exist.
Again, see the Carl Sagan quote--it's OK to postpone reaching a conclusion in the absence of evidence.
My bolding:
amb said:
If on the other hand, one looks at the age of this universe, the unlikely odds of life starting from the raw elements that were made in the original B/B, and having to be processed in giant stars that had to explode to spew material that was produced in the stars core in order for planets to form into the vast reaches of space, a cycle that is ongoing, death of one leads to life of another, the energy never dying, but recycled over and over.
Again, your reasoning here is more similar to that of Creationists/ID proponents.
How did you calculate "the unlikely odds"?
amb said:
Perhaps in some little corner of the universe, the first elements came together to produce more elements that finally over who knows how much time produced the first microbes and or cell.
I suggest you watch this video on abiogenesis again (or for the first time if you haven't yet). Please watch the entire thing--the meat of it doesn't start right away. The process is no great mystery and doesn't strain probability as you suggest.
amb said:
I have argued before, that if this planet was completely destroyed, and every hint of life came to an end. What are the chances life will once again start here like it did 4 billion years ago?
We know what's required. We at this point in time, and for the foreseeable future don't look like developing it. We need to be able to travel at least at 20% of light speed in order for us to get anywhere, and then it will probably be robots not perishable delicate humans who will do the traveling. Unless we make a superman with experimentation with the genetic code by then, maybe in 10.000 years.
If we manage to survive the next 100.000 years, the galaxy will be at our mercy. I'm certain we will have colonies on at least half the solar system, and probably robotic probes searching for signs of life in other nearby galaxies.
Really? On what grounds are you making that statement? For all we know humanity may decide that we're too big a harm to the rest of the galaxy, and be content with staying here and dying with our sun (hihgly unlikely given our evolutionary track record, but just saying that it's not an innevitability).
While this assertion isn't nearly as outlandish as your many other assertions, please try to take out the way we currently think and behave.
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